This Annex is structured into six subtasks, plus a seventh dissemination subtask, with associated activities (work packages) as outlined below. More details can be found in the Attachments at the end of this proposal narrative.
Subtask 1. Impact of Decarbonization on IEQ.
Despite growing evidence, considerable international uncertainty remains regarding the underlying drivers of IEQ changes post-retrofit. This highlights the need for harmonized methodologies and interdisciplinary research to better understand and predict the complex interactions between energy efficiency measures, IAQ, and occupant health—especially for vulnerable populations. This subtask aims to determine the most important determinants of improved IEQ from the decarbonization and retrofit of residential buildings to help drive the most optimal outcomes for residents.
Subtask 2. Multicriteria Performance-Based Ventilation for Decarbonized Residential Buildings.
Proper ventilation plays a crucial role in securing and maintaining indoor air quality (IAQ). In light of current challenges to decarbonize our buildings, it is important that such measures do not negatively impact IAQ. In many developed countries, whole house mechanical ventilation has been required for at least a decade. However, studies reveal high rates of deficiencies due to an inappropriate design, poor installation, faulty operation, and lack of maintenance during use. When mechanical ventilation is required in residencies, it is usually designed to provide minimum airflows required by local building codes. Furthermore, its performance is not always assessed from the perspective of effectiveness. We lack rating schemes with more holistic performance indicators for ventilation, based on thermal comfort, IAQ, Life Cycle Assessment-LCA and health). Even if we had suitable indicators, they would need to be incorporated during the design phase. There are innovative solutions (e.g., smart ventilation), but adoption is uncommon in contrast to prescriptive approaches that dictate fixed airflows. Innovative, performance-based solutions promise adaptation of airflows to the actual, current needs of the space, thus reducing airflows at some times and locations (energy savings) while increasing them when and where it is needed (IEQ benefits). Moreover, in the context of buildings' decarbonization (already in the European EPBD Directive), it is crucial to study the interaction between this decarbonization and the ventilation systems and its impact on overall performance (IEQ, LCA, health). This subtask aims to holistically optimize current design and operation performance assessment practices for residential ventilation so that it brings the maximum added value in retrofitted buildings.
Subtask 3. Decarbonization and Airtightness.
Research in the field of building airtightness has evolved over the last several decades. The consequences of air infiltration are usually associated with energy loss, IEQ, and poor performance of ventilation systems. A new approach is now proposed with a focus on understanding the role of building envelope airtightness in energy retrofitting of the building stock. The performance of building envelopes, pre- and post-retrofit, their mechanical properties, durability and associated whole life carbon will be studied in detail. Additionally, the consequences of improved airtightness in retrofitted buildings on IEQ will be assessed, and how they affect health and wellbeing of the occupants. A comprehensive approach will be carried out to investigate building envelope airtightness challenges; propose consistent criteria for evaluating and improving envelope performance; raise awareness, among occupants and construction agents, on the impact of building envelope on occupants’ health; and, ultimately, achieve resilient buildings.
Subtask 4. Non-Energy Impacts: Public Health Outcomes.
This subtask will develop harmonised methods for estimating the health-related non-energy impacts of residential energy upgrades, with a primary focus on indoor air quality. The work will build on established approaches such as DALYs, harm budgets, exposure-response functions, relative risks, and monetisation of health outcomes. It will produce methods, protocols, lookup resources, tools, and guidance that allow changes in indoor exposures to be translated into health-impact metrics, including avoided disease burden, healthcare costs, comparative risks, and monetised benefits where appropriate. The outputs are intended to support standards, codes, regulations, rating systems, stock-wide intervention assessments, case studies, and research. They may also inform approaches to other non-energy impacts, such as acoustic and thermal comfort, where suitable evidence and expertise are available.
Subtask 5. Implementing Performance-Based Methodologies for Ventilation in Standards and Codes.
Performance-based strategies for ventilation have been a subject of research for many years. Nevertheless, in most codes and standards globally, ventilation compliance still relies on a prescriptive approach, typically requiring a given airflow rate irrespective of actual occupancy or pollutant levels, rather than ensuring an adequate level of Indoor Air Quality (IAQ). It is now needed to transpose the robust research findings from previous Annexes into enforceable codes and standards to create a framework that encourages mass adoption (for ex. through incentive). This transposition is necessary to promote the installation of smart IAQ management systems capable of continuous optimization in buildings. Implementing such performance-based compliance pathways will simultaneously procure a tangible improvement in public health through IAQ and deliver substantial decreases in space heating and fan energy use as it will optimize ventilation flow rates.
Subtask 6. Adaptation of Solutions and Regulations to Developing Countries.
This subtask aims to gather and harmonize existing data on IAQ and residential energy use in developing countries to characterize the diversity of contexts, identify data gaps, and adapt the validated methods from Subtasks 1 to 4 to local realities and constraints. It will also propose strategies to simultaneously address energy poverty and inadequate indoor environmental quality (IEQ). Energy poverty in these regions typically results from low energy efficiency, leading to inadequate thermal comfort, poor ventilation, and unhealthy indoor conditions. These deficiencies affect occupants’ comfort, health, and well-being while revealing structural challenges in improving the energy and environmental performance of existing housing. Addressing these interconnected issues requires context-specific, cost-effective solutions that enhance energy efficiency without compromising affordability. Subtask 6 will also test the transferability of existing indicators and procedures and produce country-specific guidelines to support the development of national codes and standards, in coordination with Subtask 5.
Subtask 7. Dissemination of Project Outputs.
This subtask focuses on ensuring that the project findings are disseminated to the broad range of stakeholders. Beyond technical reports and peer-reviewed journal articles, this will include policy briefs, materials suitable for contractors, documents for manufacturers to support critical product development, and guidance for differing geographic areas and climates.